Technical Field of the Invention
This invention relates to power conversion and more particularly to wireless power conversion and supporting communications thereof.
Description of Related Art
The concept of wireless power (i.e., powering a device without an electrical power cord) has been around for a while and has recently been commercialized. In addition, there are a couple of on-going standards discussions (WPC—wireless communication alliance and CEA—consumer electronics association) to standardize wireless power systems.
Current commercially available wireless power products include a transmit unit, a receive unit, and a bidirectional control channel. In these products, the primary method of energy transfer is inductive coupling, but some lower power applications may include solar energy transfer, thermo-electronic energy transfer, and/or capacitive energy transfer. To use these products, the receive unit is a separate unit that must be coupled to a device that is to be wirelessly powered. Thus, the device itself cannot be wirelessly powered without the receive unit coupled to it.
To develop these products, effort has been spent on inductive power transfer, closed loop systems, and multiple load support. In the area of inductive power transfer, effort has been spent on optimizing the tuning the transmit and receive circuits (each of which includes a single inductor) for resonance, efficiency, and/or thermal issues, detecting loads, turning off the inductive power transfer, coil alignment, magnetic alignment, lower phantom power, Class D, E power transmitters with load compensation, antenna design, and coil switching. In the area of multiple load support, effort has been spent on power sharing and tuning, control channel multi-access, and collision avoidance.
In the area of closed loop systems, effort has been spent on regulating the transmit power, the transmit resonance, alignment to maximize safety and/or power transfer using a particular control channel protocol (e.g., backscatter, IrDA, or Bluetooth). As such, as long as the receive unit and transmit unit are from the same vendor using the same communication protocol for the control channel, wireless power transfer can occur. While the above referenced standards organization are attempting to establish standards regarding the control channel protocol, currently, vendors are free to use whatever protocol they chose, making compatibility issues between different vendors' wireless power products.